Many processes have been developed for producing hydrocarbons from various hydrocarbonaceous materials such as oil shale and tar sands. Historically, the dominant research and commercial processes include above-ground retorts and in-situ processes. More recently, encapsulated impoundments have been developed for recovering oil from crushed oil shale (In-Capsule® technology). These impoundments are formed primarily of earthen materials, with the crushed oil shale being encapsulated by an impermeable barrier made of rock, soil, clay, and geosynthetics, among other materials. The encapsulated impoundments can be very large, sometimes occupying several acres with a depth of tens of meters.
Generally, methods for recovering hydrocarbon products from oil shale have involved applying heat to the oil shale. Heating oil shale allows kerogen in the oil shale to break down through the process of pyrolysis, yielding liquid and vapor hydrocarbon compounds along with other products such as water vapor and residuals. However, the heat needed to pyrolyze oil shale is often provided by burning fossil fuels such as natural gas or a portion of the very hydrocarbons produced from the oil shale. This amounts to a significant energy expense and increases the carbon footprint of oil shale production. Accordingly, research continues into more efficient methods of producing hydrocarbons from oil shale and other hydrocarbonaceous materials.